Failed to convert value of type 'java.lang.String' to required type

[Jf Okeeffe]

I have an HTML page with a text field and a button.

When I fill the field and click enter I get the following error.

Failed to convert value of type  'java.lang.String' to required type '...model.Test'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Integer] for value 'typedvaluehere'

The code is below.

One interesting thing I noted is that when I remove extends CrudRepository<Test, Integer> from the repository, the error stops happening. But I can't do that, because I need it. But shows it seems to be a conflict with CrudRepository.

Another interesting thing I noted is that if I change "private String test" in the model to something else such as "private String name" and update getters/setters, it will work fine. Even with the CrudRepository. It doesn't work when there's a class attribute that has the same name of the model class name (ex Class Test with attribute test).

The complete project is available for download at: https://drive.google.com/file/d/1qfn73uGH6eUmJf8vtWZvbSn2IQiI0MzB/view?usp=sharing

AddTest.html

<form action="addtest" method="post">
<input type="text" name="test"/>
<input type="submit" name="btnAddTest" value="Add">
</form>

Controller

@RequestMapping(value = "/addtest", params = "btnAddTest", method = RequestMethod.POST)
public ModelAndView addTest(@ModelAttribute Test test) {

    ModelAndView modelAndView = new ModelAndView("AddTest.html");
    return modelAndView;
}

Model

@Entity
@Table(name = "Tests")
public class Test implements Serializable{

    private static final long serialVersionUID = 1L;
    
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int idTest;
        
    @Column(length=100)
    private String test;

    public int getIdTest() {
        return idTest;
    }

    public void setIdTest(int idTest) {
        this.idTest = idTest;
    }

    public String getTest() {
        return test;
    }

    public void setTest(String test) {
        this.test = test;
    }   
        
}

Repository

@Repository
@Transactional
public interface TestRepository extends CrudRepository<Test, Integer>{
    
}

[Stephan van Hulst]

I really don't see how the CrudRepository could have anything to do with it, since you are not using it in your controller at all.

[Jf Okeeffe]

Well, in the real project I do use it.
But in this test I removed it and the error still happens.

In fact, I still have these two lines (it's in the downloadable project I provided):

import projetos.repository.PessoaRepository;

@Autowired
private PessoaRepository pessoaRepository;

So, given your comment, I decided to comment those two out as well to see if the error would stop happening. No difference. The error continues there.

But if I go to the repository class and remove "extends CrudRepository<Pessoa, Integer>" the error stops happening.

So seems that even if the repository is not used, just for the fact that extending CrudRepository is there, something is being executed in the Spring backstage that is causing this error.

[Stephan van Hulst]

Can you show us the entire stack trace?

[Jf Okeeffe]

Here is what shows in the browser. In the Spring Tool Suit console no error is displayed.

Whitelabel Error Page
This application has no explicit mapping for /error, so you are seeing this as a fallback.

Sat Nov 21 16:08:42 BRT 2020
There was an unexpected error (type=Bad Request, status=400).
Failed to convert value of type 'java.lang.String' to required type 'projetos.model.Pessoa'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Integer] for value 'wer'; nested exception is java.lang.NumberFormatException: For input string: "wer"
org.springframework.beans.TypeMismatchException: Failed to convert value of type 'java.lang.String' to required type 'projetos.model.Pessoa'; nested exception is org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Integer] for value 'wer'; nested exception is java.lang.NumberFormatException: For input string: "wer"
at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:79)
at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:53)
at org.springframework.validation.DataBinder.convertIfNecessary(DataBinder.java:693)
at org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttributeFromRequestValue(ServletModelAttributeMethodProcessor.java:142)
at org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:78)
at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:139)
at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:167)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:134)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:652)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1130)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:630)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: org.springframework.core.convert.ConversionFailedException: Failed to convert from type [java.lang.String] to type [java.lang.Integer] for value 'wer'; nested exception is java.lang.NumberFormatException: For input string: "wer"
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:47)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:191)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:174)
at org.springframework.data.repository.support.DomainClassConverter$ToEntityConverter.convert(DomainClassConverter.java:177)
at org.springframework.data.repository.support.DomainClassConverter.lambda$convert$0(DomainClassConverter.java:85)
at java.base/java.util.Optional.map(Optional.java:258)
at org.springframework.data.repository.support.DomainClassConverter.convert(DomainClassConverter.java:85)
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:191)
at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:129)
at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:73)
... 52 more
Caused by: java.lang.NumberFormatException: For input string: "wer"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
at java.base/java.lang.Integer.parseInt(Integer.java:652)
at java.base/java.lang.Integer.valueOf(Integer.java:983)
at org.springframework.util.NumberUtils.parseNumber(NumberUtils.java:211)
at org.springframework.core.convert.support.StringToNumberConverterFactory$StringToNumber.convert(StringToNumberConverterFactory.java:64)
at org.springframework.core.convert.support.StringToNumberConverterFactory$StringToNumber.convert(StringToNumberConverterFactory.java:50)
at org.springframework.core.convert.support.GenericConversionService$ConverterFactoryAdapter.convert(GenericConversionService.java:436)
at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
... 62 more

[Stephan van Hulst]

Honestly, I don't know what to tell you. It seems to be some quirk of how Spring works internally, and the workaround seems to be to simply not use fields that have the same name as the class. Which I think is good advice regardless of Spring, because what does it even mean for a class "Person" to have a field named "person"?

[Junilu Lacar]

In your controller, you declared param="btnAddTest" but that's the name of the submit button. When you submit a form, the submit button isn't included in the request. What's included will be the other elements of the form, like "test" which is the name you assigned to the input text element. Spring has no way of knowing what you want to map to the test field which is why it's complaining about it.

[Junilu Lacar]

Also, the params attribute of the @RequestMapping annotation is used to route requests to different handler methods based on the value of one of the request parameters. Again, "btnAddTest" will not be included in the submitted request. Maybe you really meant to use @RequestParam("test") instead to capture the value the user typed in the text input field?

[Tim Holloway]

Junilu Lacar wrote:When you submit a form, the submit button isn't included in the request.

Allowing for whatever meddling Spring is doing, I think that's not completely true.

An HTML INPUT TYPE=SUBMIT won't submit the NAME= attribute, but it does submit the control's VALUE= attribute, which is the button's displayed value.


Also, has anyone noted that the actual exception is coming from the fact that the characters in the "number" to be converted are actually the value "wer"?

[Junilu Lacar]

Tim Holloway wrote:
An HTML INPUT TYPE=SUBMIT won't submit the NAME= attribute, but it does submit the control's VALUE= attribute, which is the button's displayed value.

Are you sure? Because if you run this example: https://www.w3schools.com/html/tryit.asp?filename=tryhtml_form_submit the submit value is not part of the request that's sent.

[Tim Holloway]

Well, that's very odd. Because long, long ago I used to do forms with multiple SUBMIT buttons and was annoyed that the SUBMIT value had to be the button label text and not just any value I wanted.

On the other hand, I just tried a form from Firefox and the URL transmitted did NOT include the SUBMIT button value. And that's not a behavior I'd expect to have changed.

It does appear that the BUTTON HTML tag can submit and send a value though.

[Stephan van Hulst]

None of that explains why the exception doesn't occur when unused repository class doesn't extend CrudRepository.

Spring seems to want to convert the input string to a number (I guess because the argument of the ID type parameter of the CrudRepository is Integer), but I don't know why Spring would do this if you're not using the repository in the first place.